If you manage a phone prospecting team, you've probably noticed: your 06 or 07 numbers get flagged much faster than your landlines. This isn't just an impression—it's a measurable fact, and there are specific reasons for it.
The Numbers: 3x More Reports on Mobile Numbers
According to aggregated data from major anti-spam databases (Truecaller, Hiya, Orange), numbers starting with 06 or 07 are reported as spam approximately 3 times more often than numbers starting with 01 to 05.
| Number Type | Prefixes | Relative Flagging Rate |
|---|---|---|
| Mobile | 06, 07 | 3x average |
| Île-de-France | 01 | 1x (reference) |
| Northwest | 02 | 0.9x |
| Northeast | 03 | 0.85x |
| Southeast | 04 | 0.95x |
| Southwest | 05 | 0.8x |
| Non-geographic | 09 | 1.5x |
This difference is explained by several converging factors.
Reason #1: Spoofing Massively Targets 06 Numbers
What Is Spoofing?
Spoofing (number impersonation) is a technique used by scammers to display a fake number on their victim's phone. And guess which numbers they use most? 06 and 07 numbers.
Why Scammers Prefer 06 Numbers
- Perceived trust: a call from 06 looks like a personal call
- "Neighbor spoofing" technique: scammers display a number with the first 6 digits identical to the victim's
- Pickup rate: people answer 06 numbers more readily than unknown numbers
Result: users have learned to be wary of unknown 06 numbers and report more easily.
Reason #2: Prospecting Volume Is Concentrated on Mobile
Sales teams massively favor mobile numbers for prospecting:
- Portability: a salesperson can use their professional 06 anywhere
- Cost: mobile plans are often cheaper than landlines
- Flexibility: ability to switch from office to field
This concentration of prospecting activity on 06 numbers mechanically creates more reports on these prefixes.
Reason #3: Psychological Perception Works Against Mobile
The Trust Paradox
When you receive a call from an 01 number, you probably think:
"It's a Paris-based company, probably legitimate."
When you receive a call from an unknown 06, you think:
"It's a telemarketer or scammer. I'm reporting it."
This perception isn't rational (a scammer can easily use an 01), but it massively influences reporting behavior.
The Mass Effect
Anti-spam apps use algorithms based on collaborative reporting. The more a prefix is reported, the more sensitive algorithms become to numbers with that prefix—creating a vicious cycle.
Reason #4: Landlines Inspire More Trust
Geographic numbers (01 to 05) benefit from several advantages:
| Advantage | Explanation |
|---|---|
| Geographic anchoring | 01 = Paris, 04 = Lyon/Marseille. This "anchors" the caller. |
| Professional image | Established companies historically have landlines. |
| Spoofing difficulty | More complex (but not impossible) to spoof a landline number. |
| Lower volume | Less prospecting = fewer reports = better overall reputation. |
What Should You Do for Your Prospecting?
Strategy 1: Mix Prefixes
Don't put all your eggs in one basket. Use a mix of:
- Landline numbers (01-05) for first contacts
- Mobile numbers (06/07) for follow-ups with "warm" prospects
- 09 numbers for professional VoIP lines
Strategy 2: Protect Your 06s with Strict Rotation
If you use 06 numbers, apply smart rotation rules:
- Maximum 35 calls/day per number
- 48-hour rest every 3 days
- Daily reputation monitoring
Strategy 3: Use 01 Numbers for Credibility
For a first contact with a strategic prospect, an 01 number will be perceived as more professional and more likely to be answered.
Strategy 4: Avoid Unintentional Spoofing
Some rotating telephony solutions may display "random" numbers that look like spoofing. Make sure your outgoing numbers are actually yours and match your company.
The Concrete Impact on Pickup Rates
Here's what we generally observe:
| Number Type | Average Pickup Rate |
|---|---|
| 01 (Île-de-France) | 18-22% |
| 02-05 (Province) | 16-20% |
| 06/07 (Mobile) | 10-15% |
| 09 (VoIP) | 12-16% |
| 06/07 flagged spam | 3-6% |
The difference is massive. A "clean" 01 number can have a pickup rate 5x higher than a spam-flagged 06.
FAQ
Are 07 numbers reported even more than 06?
07 numbers have a slight over-representation in reports because they're the most recently assigned mobile numbers—so more often used for new prospecting lines. The difference remains marginal (about +10% vs 06).
Can a landline be flagged as spam?
Absolutely. Any number used for intensive prospecting can end up flagged, regardless of prefix. Best practices apply to all number types.
Should I abandon 06 numbers for prospecting?
No, but use them intelligently. Reserve your 06s for "warm" contacts (follow-ups, existing customers) and favor landlines for cold calling.
How much does a professional landline cost?
Between €10 and €30/month depending on the carrier and options. It's a worthwhile investment if it improves your pickup rate by 50%.
To protect your mobile numbers, check our reputation score guide. And if your numbers are already blacklisted, follow our carrier unblocking guide.
Conclusion: The Prefix Is Only Part of the Equation
Yes, 06/07 numbers are reported as spam more often than 01-05. But the prefix is just one factor among many.
What really matters:
- The quality of your calls (targeting, script, respect for the prospect)
- Volume per number (avoid "carpet bombing")
- Proactive monitoring of your reputation
- Compliance with Bloctel rules
A well-managed 06 will always beat a poorly used 01. But with equal practices, landlines maintain a natural advantage.
Find out how to check your numbers' reputation regardless of their prefix.
